diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 7bcff0e094..d67780ebaf 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -1,10 +1,10 @@
 Yii Framework 2 Change Log
 ==========================
 
-2.0.43 under development
-------------------------
+2.0.42.1 under development
+--------------------------
 
-- no changes in this release.
+- Bug #18634: Fix `yii\db\BaseActiveRecord::unlink()` and `unlinkAll()` to omit condition for `on` property when it doesn't exist (bizley)
 
 
 2.0.42 May 05, 2021
diff --git a/framework/db/BaseActiveRecord.php b/framework/db/BaseActiveRecord.php
index c80528c2a2..6555cf2f5d 100644
--- a/framework/db/BaseActiveRecord.php
+++ b/framework/db/BaseActiveRecord.php
@@ -1413,7 +1413,7 @@ abstract class BaseActiveRecord extends Model implements ActiveRecordInterface
             foreach (array_keys($columns) as $a) {
                 $nulls[$a] = null;
             }
-            if ($viaRelation->on !== null) {
+            if (property_exists($viaRelation, 'on') && $viaRelation->on !== null) {
                 $columns = ['and', $columns, $viaRelation->on];
             }
             if (is_array($relation->via)) {
@@ -1513,7 +1513,7 @@ abstract class BaseActiveRecord extends Model implements ActiveRecordInterface
             if (!empty($viaRelation->where)) {
                 $condition = ['and', $condition, $viaRelation->where];
             }
-            if (!empty($viaRelation->on)) {
+            if (property_exists($viaRelation, 'on') && !empty($viaRelation->on)) {
                 $condition = ['and', $condition, $viaRelation->on];
             }
             if (is_array($relation->via)) {
@@ -1550,7 +1550,7 @@ abstract class BaseActiveRecord extends Model implements ActiveRecordInterface
                 if (!empty($relation->where)) {
                     $condition = ['and', $condition, $relation->where];
                 }
-                if (!empty($relation->on)) {
+                if (property_exists($relation, 'on') && !empty($relation->on)) {
                     $condition = ['and', $condition, $relation->on];
                 }
                 if ($delete) {